J/ApJ/497/736 The young cluster IC 348. (Herbig, 1998)
The young cluster IC 348.
Herbig G.H.
<Astrophys. J. 497, 736-758 (1998)>
=1998ApJ...497..736H 1998ApJ...497..736H (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, open ; Photometry, UBVRI ; Photometry, CCD
Keywords: open clusters and associations: individual (IC 348) -
stars: emission line, Be - stars: luminosity function, mass function -
stars: pre-main-sequence
Abstract:
CCD photometry in BVRI was obtained for about 260 stars in and around
IC 348, and multiobject spectroscopy for 80 of these. A somewhat
larger region was surveyed for stars having Hα in emission; over
110 emission-line stars brighter than about R=19 were discovered.
Because Hαemission could be detected to a limit near W=3Å,
division into weak-line (WTTSs) and classical T Tauri stars (CTTSs)
was possible on purely spectroscopic grounds. There is a steep rise in
the number of emission-line stars below W(Hα)=10Å; the
proportion of WTTSs to CTTSs in the area surveyed is 58:51. ROSAT
detected only about 58% of the spectroscopic WTTSs and about 65% of
the CTTSs, although these numbers are sensitive to the survey
thresholds. The bulk of the ages of about 100 stars, read off the
theoretical tracks of D'Antona & Mazzitelli (1994ApJS...90..467D 1994ApJS...90..467D),
range between about 0.7 and 12Myr, but the emission-line stars, which
are most likely to be members of IC 348, have a mean age of 1.3Myr.
Allowance for unresolved binaries would increase this somewhat, but
there is a firm upper limit at 2.95Myr. There is no indication that
the ages of the emission-line stars depend upon W(Hα): the IC
348 WTTSs as a population are not systematically older than the CTTSs,
but there is a tendency for the WTTSs to be concentrated toward the
center of IC 348, while the CTTSs are more widely distributed. There
is a scattering of emission-Hα stars over the entire area
surveyed. There are too many to be explained as low-mass members of an
earlier generation of star formation in Per OB2 or as foreground dMe
stars. The mass frequency function, based on some 125 stars fitted to
theoretical tracks, rises from 1.5M☉; to about 0.2M☉;, with a
slope very much like that of the Scalo initial mass function. The
optical cluster IC 348 radius is about 4.0', or 0.37pc. The total
mass of optically detectable stars in this volume is 57M☉;, while
the mean space density is about 520 stars/pc3. The amount of
interstellar material remaining within the cluster is small in
comparison. Star formation in the Per OB2/IC 348 region cannot be
characterized by one unique age; it appears that stars have been
forming in the region now occupied by the association for 10-20Myr.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1a.dat 94 261 Photometry of IC 348 region stars
table5.dat 26 25 Comparison of types from UBV photometry and
from spectral classification
table6.dat 48 44 Additional Hα-emission stars
--------------------------------------------------------------------------------
See also:
J/A+A/324/549 : Deep UVBRI photometry in IC 348 (Trullols+ 1997)
II/197 : ISM towards IC 348 and Per OB2 (Cernis, 1993)
Byte-by-byte Description of file: table1a.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- Seq Sequential number (Cl* IC 348 H NNN in Simbad)
4 A1 --- n_Seq [defgh] Note (1)
6- 8 I3 --- TJ ? Trullols & Jordi (1997, Cat. J/A+A/324/549)
number (2)
10- 12 A3 --- IfAHA IfAHα (NN) or LkHA (LNN) designation
14- 15 I2 --- [PZH96] ? Rosat source number (1996A&A...310..456P 1996A&A...310..456P)
16 A1 --- u_[PZH96] [?] Uncertainty flag on [PZH96]
18- 19 I2 h RAh Right ascension (1950)
21- 22 I2 min RAm Right ascension (1950)
24- 28 F5.2 s RAs Right ascension (1950)
29 A1 --- DE- Declination sign
30- 31 I2 deg DEd Declination (1950)
33- 34 I2 arcmin DEm Declination (1950)
36- 39 F4.1 arcsec DEs Declination (1950)
41- 45 F5.2 mag Vmag ? V magnitude
47- 50 F4.2 mag B-V ? B-V colour index
51 A1 --- u_B-V Uncertainty flag on B-V
53- 57 F5.2 mag V-I ? V-I colour index
59- 62 F4.2 mag V-R ? V-R colour index
64- 68 F5.2 mag Rmag ? R magnitude
70- 73 F4.2 mag R-I ? R-I colour index
75- 78 A4 --- Var Variable?
80- 82 A3 --- SpType Spectral type
83 A1 --- n_SpType [c] Note on spType (3)
85- 87 I3 0.1nm W(Ha) ? Hα width
88- 89 A2 --- u_W(Ha) [: ] Uncertainty flag on W(Ha)
91- 94 A4 --- n_W(Ha) Note on W(Ha)
--------------------------------------------------------------------------------
Note (1): d: The spectrum is overlapped by that of 261, so W(Ha) is very
uncertain.
e: Both components of this close pair (109 and 110) have Ha emission,
but W(Ha) refers to the combined spectrum
f: On one MOS spectrogram W(Ha)=230Å
g: On one MOS spectrogram W(Ha)=170Å
h: The spectrum is severely overlapped by that of 157.
Note (2): Cl* IC 348 TJ NNN in Simbad
Note (3): c: Spectral types from Harris et al. 1954 or Strom et al. 1974.
--------------------------------------------------------------------------------
Table 1B. Correspondence between the several numbering systems
--------------------------------------------------------------------------------
Number Gingrich Fredrick Cernis 1993
1922ApJ....56..139G 1922ApJ....56..139G 1956AJ.....61..437F 1956AJ.....61..437F Cat. II/197
--------------------------------------------------------------------------------
20 IC 348 3 Cl* IC 348 F 7 [C93] 62
83 IC 348 6 Cl* IC 348 F 10 [C93] 66
89 IC 348 7 Cl* IC 348 F 11 [C93] 68
103 IC 348 8 Cl* IC 348 F 12 [C93] 69
137 [C93] 75
144 Cl* IC 348 F 16 [C93] 76
166 IC 348 13 Cl* IC 348 F 19 [C93] 79
252 IC 348 10 Cl* IC 348 F 14 [C93] 73
254 IC 348 11 Cl* IC 348 F 15 [C93] 74
261 IC 348 9 Cl* IC 348 F 13 [C93] 70
--------------------------------------------------------------------------------
Table 1C. Stars with fainter companions
----------------------------------------------
Number d PA Imag
(arcsec) (deg) (mag)
----------------------------------------------
115 1.7 291 3.1:
136 0.7 213 0.8:
159 1.3 132 3.8:
204 0.8 8 1.5:
211 1.0 160 2.6:
229 1.0 6 1.3::
----------------------------------------------
Byte-by-byte Description of file: table5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- TJ TJ (Trullols & Jordi, 1997, Cat. J/A+A/324/549)
number
5- 8 A4 --- PType Photometric type
10- 13 F4.2 mag AVph Photometric visual extinction
15- 17 I3 --- Seq Sequential number
19- 20 A2 --- SpType Spectral type
21 A1 --- n_SpType [*] Note on SpType
23- 26 F4.2 mag AVsp ? Spectroscopic visual extinction from V-I excess
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table6.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 A4 --- IfAHA IfAHα (NN) or LkHA (LNN) designation
5 A1 --- n_IfAHA [a] a: IfAHA 8 and 66 form a pair about 2" apart
7 I1 h RAh Right ascension (1950)
9- 10 I2 min RAm Right ascension (1950)
12- 16 F5.2 s RAs Right ascension (1950)
17 A1 --- DE- Declination sign
18- 19 I2 deg DEd Declination (1950)
21- 22 I2 arcmin DEm Declination (1950)
24- 27 F4.1 arcsec DEs Declination (1950)
29- 31 I3 0.1nm W(Ha) ? Hα line width
32 A1 --- u_W(Ha) Uncertainty flag on W(Ha)
33- 36 A4 --- n_W(Ha) Note on variability of W(Ha)
38- 40 I3 --- [PZH96] ? ROSAT source number (1996A&A...310..456P 1996A&A...310..456P)
41 A1 --- u_[PZH96] [?] Uncertainty flag on [PZH96]
43- 46 F4.1 mag Rmag R magnitude
47- 48 A2 --- u_Rmag [: ] Uncertainty flag on Rmag
--------------------------------------------------------------------------------
History: From ApJ electronic version
(End) James Marcout, Patricia Bauer [CDS] 16-Jun-1998